Means for controlling electric-motor vehicles.



No. 682,642. Patented Sept. l7, IBM. J. SACHS. IEAIS FOR CONTROLLINGELECTRICIOTOB VEHICLES.

(Application filed July 28, 1000.) (In Iodql.) 2 Shouts-Shoat I.

No. 682,642. Patented Sept. I7, IBM. J. SACHS. IEANS FOR CONTROLLINGELEOTRICIOTOR VEHICLES. (Apphcahon fllod July 26, 1900) 2 Shah-Shoe! 2.

(No Model.)

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UNITED STATES PATENT OFFICE.-

JOSEPH SACHS, OF HARTFORD, CONNECTICUT.

MEANS FOR CONTROLLING ELECTRIC-MOTOR VEHICLES.

SPECIFICATION forming part of Letters Patent NO. 682,642, datedSeptember 17, 1901.

Application filed July 26, 1900. Serial No. 24;.870. (Nu model T0 rtZZwhont it ntcty concern:

Be it known that I, JOSEPH SAoHs, a citi- Zen of the United States,residing at Hartford, in the county of Hartford and State ofConnecticut, have invented a new and useful Improvement in Methods ofand Means for Controlling Electric-Motor Vehicles, of which thefollowing is a specification.

My present invention relates to means for controlling the currentdelivered to an electric motor used in propelling motor-vehicles andsimilar conveyances or in driving machinery.

The storage batteries of the present storage-battery-motor vehicle arehampered by the fact that the battery discharge is constantly varyingand at times far exceeds the discharge rate at which the battery may beadvantageously run. This is caused by the demand of the motor for avarying current to supply the necessary torque output at thevehicle-wheels to keep them in motion under all conditions of travel,ascending grades and rough roads necessarily requiring greater torqueoutput to keep the vehicle in motion than level and good roads. Thisvariable discharge of the battery at rates which often exceed theefficient discharge rate shortens the life and reduces the total outputcapacity of the battery, because a storage battery will only operateeiiiciently when the rate of discharge is such that the chemical changein the plates is not excessive. It is therefore desirable in vehiclesusing storage batteries to limit the battery discharge to an economicalrate, and so prolong the battery capacity.

The object of my invention is therefore to provide means automaticallyoperated whereby a practically constant current is supplied to the motorfrom a battery or other source and at the same time provide meanswhereby automatically the motor can deliver a variable torque, saidtorque varying inversely as the speed of the motor.

Referring to the drawings, Figure 1 is an elevation and diagrammaticview of a means for accomplishing the objects of my present invention.Fig. 2 represents an equivalent form of the device. In Fig. 3 I haveillustrated my invention as applied to a motorvehicle. Figs. 4, 5, and 6are modified forms of the device shown in Figs. 1 and 2, illustrating,respectively, a separately excited motor-field, an armature loose uponits shaft, and an adjustable field-pole.

Referring to Fig. 1, a represents a storage battery, and Y) represents acontroller; but neither of the above has any bearing on the presentinvention, they being shown simply to indicate a source of power andmeans for controlling the same. dis a motor-armature, and c themotor-field, which,as will be seen, is represented as series wound. Thefields are wound in sections, successive sections being connected tocut-out terminals 4, 5, 6, 7, 8, 9, and 10, respectively. Upon themotor-shaft I employ a ball-governor e. One of the governor sleeves e ispinned to the shaft. The other sleeve 6 is loose upon the shaft andcarries the lever-arm f,whichispivoted atend i. The lever h is pivotedat it, having on the opposite end a contact-piece adapted to bear uponany one of the cut-out terminals 5 to 10, inclusive. Levers f and h areconnected by tie-rod g. I do not limit myself to these devices forcontacting with the cut-out terminals, as other devices actuated by thegovernor may be equally operative and advantageous. In other Words, anykind of motor may be employed and the field varied in any desirable way.It is well understood that the speed of any given electric motor variesdirectly as the impressed voltage at its terminals and inversely as thefield strength; also, the torque delivered by said motor dependsdirectly upon the current passing through the armature and the strengthof the motorfields.

To illustrate the device represented in Fig. 1, we will assume that thesame is attached to a motor-vehicle and that said vehicle is runningsmoothly along a level road. Under these conditions it is assumed thatthe motor requires a certain definite current strength to deliver thenecessary torque to propel the vehicle, said current strength not toexceed the efficient discharge rate of the battery. If now the vehiclecomes to an ascending grade or obstruction requiring an increased torqueoutput of the motor, the motor obviously demands an increase of currentand slows'down. At the same time the governorballs approach one another,thereby operating the lever h through the rod 9 and lever fto throw inone or more sections of fieldcoils, and thus increase the fieldstrength. It will thus be apparent that any demand upon the motor todeliver an increased torque is supplied at a practically constantcurrent by an increased field strength and a decreased speed. When thevehicle comes again to an ordinary level road, the tendency is for thecurrent supplied to the motor to decrease and the speed to increase,efiecting the controlling device in the opposite way, cutting out one ormore of the field-sections, weakening the field strength, and reducingthe torque output of the motor, which now operates at an increased speedand bringing the current again to its efficient output rate. The motoris thus being operated at a practically constant energy output.

In Fig. 2 I have shown a shunt-wound motor. The lead L and L comingfromasuitable source of power, as shown in Fig. 1, relative motion istransmitted to the supplemental shaft 7' from motor-shaft through gearsland Z. I Upon the shaftr is a loose sleeve 0", having integral flanges12 and 13. A lever m is attached to one end of the sleeve 1", said leverbeing pivoted at m. A circular disk 11 is attached to the lower end of ascrew-rod v and the latter is actuated through the disk 11 by disk 11coming in contact with either flange 12 or 13; The arm a is movedvertically by said feed-screw v and is adapted to bear successively uponthe terminals of rheostat k, which is in the field-circuit. A. solenoidu is in the main circuit and arranged to actuate the lever m. Theoperation of this and the preceding device is precisely similar. When ademand for increased torque is made upon the motor, the latter demandsan increase of current. This increase of current in its initial stage,acting through the solenoid t, draws the lever m over, and consequentlythe sleeve r, until flange 12 comes in contact with the disk 11. Saiddisk is then revolved and the arm a raised, whereby the resistance inthe field-circuit is decreased and the field strength increased. Thusthe additional torque required of the motor is supplied at a nearlyconstant current by an increasejof field strength and decrease of speed,and vice versa.

Fig. 4 is a variation of Fig. 2, wherein the motor-field is separatelyexcited, the intensity of the field being varied by the same device, asshown in Fig. 2, said device throwing in or cutting out cells of thebattery employed to excite the motor-field to increase or diminish thefield strength, as the case may be.

Fig. 5 illustrates a modification of my invention, wherein themotor-armature is loose upon its shaft and is coupled to the loosesleeve of governor 6, whereby the armature 1s moved in and out of themagnetic field, ac-

cording to a decrease or increase of motor speed. An increased torque isthus applied at a decreased speed and increased flux through thearmature, and vice versa.

Fig. 6 is a modification of the means of varying the magnetic fluxthrough the motorarmature by automatically increasing or decreasing theair-gap and producing the same eifect as in the previous modification.

It will be understood that in applying this invention to motor-vehiclesit is essential to employ a motor of massive field, the fields being ofheavier construction than is necessary for the operation of the motorunder normal conditions on level roads.

I claim as my invention-- 1. In an electric-motor-controlling system,the combination with a source of electric energy and theactuating-motor, of devices for automatically varying the field strengthof the motor whereby, without an increased current-supply from thesource of electric energy, any additional torque demanded of the motoris delivered at a decreased speed and vice versa, substantially asspecified.

2. In an electric-motor-controlling device the combination with a sourceof electric energy and the actuating=motor, of a device an tomaticallyactuated by the motor-shaft and shifted by the variable speed thereof,for varying and so regulating the strength of the motor-field, wherebywithout an increased current-supply from the source of electric en ergy,any additional torque demanded of the motor is delivered at a decreasedspeed and vice versa, substantially as specified.

3. In an electric-motor-controlling device, the combination with asource of electric energy and the actuating-motor, of a device au=tomatically actuated by variations in the current-supply to said .motor,and devices automatically actuated by the motor-shaft and shifted by thevariable speed thereof for varying and so regulating the strength of themotor-field, whereby without an increased current-supply from the sourceof electric energy, any additional torque demanded of the motor isdelivered at a decreased speed and vice versa, substantially asspecified.

'4. In an electric-motor vehicle the combination with a source ofelectric energy and controller therefor, of an electric motor con nectedto the driving-axle of said vehicle and devices for automaticallyvarying the field strength of the motor whereby, without an increasedcurrent-supply from the source of electric energy, any additionaltorque. demanded of, the motor is delivered at a decreased speed andvice versa, substantially as specified.

5. In an electric-motor vehicle, the combination with a source ofelectric energyand controller therefor, of a series motor whosefield-coils'are made in sections connected to the axle of said vehicle,of a governor on the shaft of such motor, of means connected to andoperated by said governor and electric connections, whereby an increaseor decrease of the torque demanded of said motor is automaticallysupplied, by a decrease or an increase of field strength and a decreaseor an increase of speed, at a practically constant current-supply fromthe source of electric energy to motor, substantially as specified.

6. In an electric-motor vehicle, the combination with the source ofelectric energy and controller therefor, of an electric motor connectedto the driving-axle of said vehicle, a centrifugal governor on the shaftof said motor, a series of cut-out terminals electrically connected tosuccessive sections of the m otorfields and devices actuated by thevarying speed movements of the governor for successively contactin gwith said terminals, whereby the field strength is increased ordecreased to compensate for the varying torque demanded of the motor,substantially as specified.

7. In an electric-motor vehicle the combination with a source ofelectric energy and controller therefor, of an electric motor connectedto an axle of said vehicle and devices which automatically vary thetorque and speed of the motor without changing its output, with aconstant current flow and fixed electromotiye force at its terminals,substantially as specified.

8. In a system of electric-motor-vehicle control the combination with anelectric motor and a source of electrical energy therefor, of devicesfor automatically Varying the torque and speed of the motor inversely,without aflfecting either the motors energy output, the potential at itsbrushes, or the current supplied thereto, substantially as described.

9. In a system of motor-control, the combination with an electric motorand a source of electrical energy, of devices for manually regulatingthe movement and speed of the motor, and devices for automaticallyeffecting an inversely Variable speed and torque in the motor at a givenenergy input, without changing either the motors energy output, thepotential at its brushes, or the current supplied thereto, substantiallyas set forth.

Signed by me this 23d day of July, 1900.

JOSEPH S ACHS.

Witnessesi GEo. T. PINCKNEY, BERTHA M. ALLEN.

